NON RAS ONCOGENES IN CHEMICALLY INDUCED RAT LIVER TUMORS

肝细胞癌是人类的主要肿瘤之一。这个 RAT提供了最具特色的模型系统之一 化学诱导肝细胞发育的研究进展 癌症。尽管在分离和分离方面取得了快速进展 一系列其他原癌基因激活的特征 系统中，关于肝脏的此类报道相对较少。 肿瘤，尤其是老鼠体内的肿瘤。甲基(乙酰氧甲基) 亚硝胺(DMN-OAC)是一种“有条件的”致癌物质 仅当注射到正在接受手术的动物体内时才会产生肿瘤 活跃的肝脏再生。我们已经提取了8点的DNA样本 DMN-OAC诱发大鼠原代肿瘤转化能力的研究 将其导入NIH3T3细胞。在8个原发肿瘤中有7个 我们检测到了转化活性。形态上的 转化的NIH3T3细胞在软琼脂中生长， 在接种到裸鼠体内后，都会致癌。 因为我们之前已经描述了几个 大鼠肝脏再生生长过程中的原癌基因 从NIH3T3转化子中检测DNA中的ras(N- Ras、rash或rasr)、myc、erba、erb、V-raf、A-raf或neu基因 没有发现任何与这些基因有关的证据。 日本血吸虫限制性内切酶敏感性图谱的初步研究 初级转化子DNA表明至少有3个 本能基因在我们所处的一组肿瘤中被激活 正在检查。这项研究项目的主要重点将是 通过分子克隆分离这些基因中的每一个 根据基因在两个正常人群中的表达情况来表征 大鼠组织和DMN-OAC诱导过程中的变化 致癌。进一步研究这些基因的特征将会 包括将基因导入大鼠肝脏“卵圆”细胞系 并转化为具有增强增殖能力的肝细胞。在……里面 在项目的后期阶段，我们将表达这种蛋白质 利用杆状病毒表达系统表达这些基因的产物 并从细胞角度对癌基因蛋白进行了表征 免疫荧光法进行组织定位。最终我们 希望确定这些原癌基因在两种正常组织中的作用 大鼠发展与肝细胞癌的发生发展。

Hepatic cell carcinoma is one of the major tumors of man. The rat offers one of the best characterized model systems for examining the development of chemically-induced hepatic cell carcinoma. Despite the rapid advances in isolating and characterizing activated proto-oncogenes in a number of other systems, there have been relatively few such reports of hepatic tumors, particularly in the rat. Methyl (acetoxymethyl) nitrosasmine (DMN-OAc) is a "conditional" liver carcinogen producing tumors only when injected into animals undergoing active liver regeneration. We have enxamined DNA from 8 primary rat tumors induced by DMN-OAc for transforming ability upon transfection into NIH3T3 cells. In 7 of the 8 primary tumors we have detected transforming activity. The morphologically transformed NIH3T3 cells grow in soft agar and those which have been tested are tumorigenic upon inoculation into nude mice. Since we have previously characterized the expression of several proto-oncogenes during regenerative growth in rat liver, we examined DNA from the NIH3T3 transformants for altered ras (N- ras, rasH or rasR), myc, erbA, erb, V-raf, A-raf or neu genes and have found no evidence for any involvement of these genes. Preliminary restriction endonuclease sensitivity profiles of the primary transformant DNA suggest that there are at least 3 dinstinct genes activated whithin the set of tumors we are examining. The major focus of this research project will be to isolate each of these genes by molecular cloning and to characterize the genes with respect to expression in both normal rat tissues and during the course of DMN-OAc induced carcinogenesis. Further studies characterizing these genes will include transfection of the genes into rat liver "oval" cell lines and into hepatocytes with enhanced proliferative capability. In the later stages of the project we will express the protein products of these genes using the baculovirus expression system and characterize the oncogene proteins with respect to cellular and tissue localization by immunofluorescence. Ultimately we hope to define the role of these proto-oncogenes in both normal rat development and the development of hepatic cell carcinoma.